Imagine tromping through 40 miles of the densest portion of the Withlacoochee River, the roughly one mile wide slow moving Green Swamp. Dr. Mark Fulkerson, Senior Professional Engineer with the Water Management District did so with a small team, in order to map out the bottom and acquire elevations of the river bed. According to Dr. Fulkerson, it took a couple summers to finally get to the Hernando County line, where a surveying company took over. Being so dense, “The survey company would not touch the Green Swamp,” said Dr. Fulkerson at a recent lecture. In 2007 his team included Buddy Brass a contracted employee and intern Ben Nelson while in 2008 Buddy Brass and Bryan Delius, also a contracted employee, helped out.
For many, the Green Swamp is most likely not the ideal work environment, however Dr. Fulkerson is not among the many. “I’ve got probably the best job in the world,” stated Dr. Fulkerson. That is because he explained, “I get to work on a lot of the systems that as a kid I grew up and paddled down and camped along.” He has created a career out of a lifelong passion.
The survey data obtained by Dr. Fulkerson and his team was used along with additional survey data of the rest of the river to create a modeling system of how water flows in the river. The model allows them to determine what might currently be affecting the flow and how any proposed change would affect the flow in the future. This project is called the Withlacoochee River Watershed Initiative, headed up by Dr. Fulkerson.
Dr. Fulkerson described the geography of the Withlacoochee River. The river is 160 miles long, one of the longest in state. It is made up of streams, lakes and wetlands. The Withlacoochee Watershed begins in Polk and Lake counties encompassing over 2000 square miles and all or part of 8 counties. A watershed is defined as an area of land that water flows across as it moves toward a common body of water. From its origins in Polk and Lake County, the Withlacoochee flows west and north eventually discharging into the Gulf. The river itself is quite diverse. Dr. Fulkerson stated, “As we look at the Withlacoochee watershed, the characteristics change drastically as it flows over the 160 mile length.”
At the beginning of the river, Dr. Fulkerson explained the Green Swamp is a vast area with the highest water levels of the aquifer system. This is the mechanism that helps feed the Withlacoochee and other river systems. He stated that because of this, the Green Swamp is a critical area. In some areas of the Green Swamp there is no channel as the river flows through vast swampland.
Once the river reaches the towns of Lacoochee and Trilby in the northern end of Pasco and southern Hernando County, the river becomes confined with high banks. Suddenly, the water moving out of the Green Swamp is channeled into a more contained area. Dr. Fulkerson explained for that reason, there is a history of flooding in this area.
The river then flows into the heart of Hernando County at Silver Lake which is directly off of I75. As the water moves out of Silver Lake downstream, it flows into the Croom Wildlife Management area. The Withlacoochee comes through around Hog Island. In some years like in 2007, the Withlacoochee will dry up and be contained within Silver Lake.
Continuing downstream into the borders of Sumter and Citrus County, Dr. Fulkerson explained, “that the river which has been confined by high banks for awhile spreads out massively once again near the Tsala Apopka chain of lakes.” Dr. Fulkerson added, “There is a lot of marshland that fills up between the river and those lakes.” The river is no longer contained in a single channel, is wide and relatively shallow near Tsala Apopka. Today canals are the main thoroughfare for water flowing between the Withlacoochee and Tsala Apopka chain of lakes.
Rounding the horn of the Tsala Apopka area, the Withlacoochee starts to confine again with high banks near Dunnellon. Near Lake Rousseau the Withlacoochee River was historically a winding meandering river. Today it is drastically different. In the early 1900’s, Florida Power Corporation built Inglis dam on the river, creating Lake Rousseau. The Inglis Dam, Barge Canal, and Bypass Channel are downstream of Lake Rousseau. The Lower Withlacoochee which begins at the most south western part of Lake Rousseau is a winding meandering river that joins with the Cross Florida Barge Canal that then flows directly to the Gulf of Mexico. The main part of the Withlacoochee River is channeled off of Lake Rousseau through a canal system. At a point just north of where the lower Withlacoochee runs into the Cross Florida Barge Canal, the channeled Withlacoochee is allowed to progress naturally on a winding northwestward path to Inglis and Yankeetown where it then heads south to the Gulf of Mexico.
Dr. Fulkerson emphasized that just as important as the river’s diverse features, is its natural fluctuations with flooding and droughts. He explained that most recently in 2012 we had very low water on the river. The name Withlacoochee extends from the Creek Indian term for the river “WeThalkoChee” meaning Little-Big-Water. Dr. Fulkerson postulated that this “likely refers to high and low fluctuations” of the river.
In examining general trends from regional rainfalls, Dr. Fulkerson pointed out that years with above average and below average rainfall alternate regularly. However in the past 30 years, there have been more years with below average rainfall. He also explained why the great flood of 1960 was such a devastating flood event, stating that massive above average rainfall for the previous three years contributed greatly. The ground had already been saturated with water when Hurricane Donna hit. During Tropical Storm Debbie, we were coming out of a drought period in 2012. Dr. Fulkerson stated that Debbie’s rainfall filled our systems back up. He pointed out however that if we started at higher water levels, flooding could have been more of a problem.
Dr. Fulkerson explained that widespread awareness of the Withlacoochee River and its tendency for large fluctuation occurred during the Second Seminole War. A large number Seminoles lived in the region of the Tsala Apopka chain of lakes, which is historically referred to as The Cove of the Withlacoochee. The Cove was a Seminole stronghold but also has earlier historical significance. Many attempts were made on taking the Cove during the Second Seminole War, but none were very successful. In one attempt led by Governor Call, they were unable to ford the river due to flooding. They found themselves under pressure by the Seminoles and without axes to build rafts. Additionally, their supply boat sunk on the lower part of the river. It was headed up the Withlacoochee from the Gulf to a supply base. With a lack of food, Governor Call brought the expedition back to Fort Drane.
Dr. Fulkerson explained that the army faced many problems with trying to get the army’s shallow draft steamboats upriver to bring supplies. Because the river is rather shallow throughout they had many navigation issues. He referred to communications that have been found regarding surveying the river to determine where rocks needed to be removed to get the steamboats upriver. The army did remove rocks, but found that they could still only navigate when the water was up from rainfall.
Following the Seminole Wars, several industries began to boom around the region, including phosphates, timber and citrus. Naturally, the river was altered by these industries in one way or another. Dr. Fulkerson explained that many areas were mined and dredged out of the Withlacoochee River. Evidence of this can be seen up around Dunnellon where there are coves off of the river with pilings and wooden remnants from mining. Dr. Fulkerson pointed out that before they created Lake Rousseau from the Inglis Dam, water levels were 20 feet lower than they are today.
Ancient cypress 2000 to 3000 years old were logged out of the river. Dr. Fulkerson stated that in the Green Swamp there are giant stumps in the flood waters from these ancient trees some as tall as him.
Navigation on the river was extremely important to support these industries. The canals built between the Withlacoochee and the Tsala Apopka chain of lakes referred to earlier were dug in order to provide the citrus industry a way to transport their product to the railroad. In the timber industry, particularly in the Green Swamp, they brought a railroad in and spurred off tram roads into the swamp to transport the cypress they were logging. When they did that, Dr. Fulkerson explained, they’d drive the pilings down, lay a strip of steel track on top and kept going. Some of these railroads still exist. Dr Fulkerson is interested in answering the question “How has railroad affected the river?”
The Withlacoochee River Watershed Initiative addresses concerns like these about the river and it looks at the river system as a whole to better understand it. Dr. Fulkerson explained that they aim to determine the effects of alterations, and best management/restoration practices through the use of the computer model.
Hydrographic survey mapping and topographic mapping were both performed in order to build the modeling system. When Dr. Fulkerson and his team walked 40 miles through the Green Swamp, they were working on the hydrographic survey. They used basic surveying tools which included a water level gauge with an elevation on it, a rod and level to take an elevation every hundred feet or so. Newer technology doesn’t work in dense canopy. Overall several thousand river bottom elevations were collected within this 40 miles.
Through the topographic mapping of land elevations for the entire watershed they are trying to determine how a change such as a berm or culvert affected the river over time. Dr. Fulkerson wishes to answer questions such as if it rains somewhere over by Lake Panasoffkee, if when and how does that water get into the river.
Aerial surveying to acquire elevations unfortunately cannot be used here in Florida since the waterways tend to be murky. In some places it can be used where there is a sandy bottom and clear water so the river beds can be detected from above. They blend together aerial elevations with manually obtained elevations of the river’s bottom. This provides them with an excellent picture of the topography of the river bottom including all the fishing holes as well as rocks that obstruct flow.
The comprehensive model of the entire watershed has been used to answer many questions about the river as well as issues and concerns that had been expressed by the public. They have addressed the questions and concerns through nineteen modeling scenarios at various locations along the river. These include questions about the effects of bridges, berms, culverts, altering water conservation structures, dredging canals and the effectiveness of proposed flood prevention strategies. Dr. Fulkerson explains, “The scenarios are not projects but rather evaluations to better understand how historical alterations or future changes would affect the river.”
The following list describes the breakdown of the 19 scenarios:
“Five scenarios in the Green Swamp relating to berms, ditches, bridge pilings and historical rock formations.
Six scenarios in the Tsala Apopka chain-of-lakes related to flooding, low water levels, structure operations and pre-settlement conditions.
Two scenarios in the Lake Rousseau area related to conveyance of water through the Bypass Spillway to the lower Withlacoochee River.
Six scenarios at various locations along the river related to flooding, low water levels and structure operations.”
The results of the 19 modeling scenarios can be found at: http://www.swfwmd.state.fl.us/files/database/site_file_sets/2615/Scenarios_01_to_19_lettersize.pdf
According to Dr. Fulkerson, the model will continue to be used to address future concerns and evaluate additional scenarios as needed. The Withlacoochee is an invaluable asset to our region. The more we understand it’s workings, the better we can preserve the asset and its value.
